1. Field of the Invention
The present invention relates to an improved call signal conversion apparatus for an elevator system.
2. Description of the Prior Art
The elevator system equipped with a digital apparatus such as a computer needs to have hall call buttons and car call buttons and registration lamps which are connected with the buttons to turn-on with each call signal and a signal conversion circuit of converting the call signal to a control device of the computer.
The apparatus having a call detection circuit and a call registration lamp-operating circuit as shown in FIG. 1 has been proposed as the signal conversion circuit (U.S. Pat. No. 4,376,930).
In FIG. 1(a), the reference numeral (1) designates a call button; (2) designates a call registration lamp; (3) designates an elevator control device. The call buttons (1) and the call registration lamps (2) are connected in series between a power source terminal P and the earth. The connected point (a) of them is connected through a common signal wire (7) for transmitting the call signal and call registration signal to the detection circuit (5) and the call registration lamp-operating circuit (6) for the call signal conversion circuit (4). The call signal conversion circuit (4) and the elevator control device (3) are connected to transmit the signals to each other.
In FIG. 1(b), the signal lines for the call button (1) and the call registration lamp (2) are separated to be capable of cutting service to selected floors. The call button (1) is connected through the call signal line (7a) between the call detection circuit (5) and the earth. The call registration lamp (2) is connected through the signal line (7b) between the call registration lamp-operating circuit (6) and the power source terminal P. Between the call signal conversion circuit (4) and the elevator controlling device (3), the transmission of the signal is imparted depending upon the call data.
In the apparatus having the above-mentioned structure, the call detection circuit (5) comprises a detection device for detecting the call signal from the call button (1) and a logic circuit for transmitting the call data to the control device (3) depending upon the data requiring timing of the control device (3). When the control device (3) receives the call data from the call detection circuit (5), the call data is memorized (registered) and the turn-on command for turning on the corresponding call registration lamp (2) is transmitted to the call registration lamp-operating circuit (6) depending upon the registration. The call registration lamp circuit (6) is controlled by the logic circuit for controlling call registration lamps and an operating circuit controlled by the output of the logic circuit. Thus, the call registration lamp (2) is turned on by receiving the command of the control device (3) into the call registration lamp circuit (6).
In the circuit having the structure shown in FIG. 1(a), the call button (1) and the call registration lamp (2) are connected in series to the power source. Even though the call registration is not desired (referred to as a floor where service is cut), the call registration lamp (2) is turned on during the operation of the call button (1). Therefore, it is not clearly indicated whether service is cut to the floor or not. Thus, this causes unreliable feeling for passenger and this is not suitable for controlling the elevator system.
In the conventional system, in order to overcome the problem when the service is cut, the call signal line (7a) and the call registration signal line (7a) are separated in the circuit as shown in FIG. 1(b) whereby the detection of the call button (1) and the control of the call registration lamp (2) are independently performed. However, twice as many signal lines than exist in the structure shown in FIG. 1(a) are needed in the latter structure. The three kinds of signals needed are the car call, the up hall call and down hall call. Therefore, 6 signal lines are needed for one floor in the structure shown in FIG. 1(b). The number of the lines is increased in proportional to the number of the elevator service floors whereby the cost and processes for construction are disadvantageously increased.